1. Field of the Invention
The present invention relates to baggage inspection systems, and in particular to such systems having a conveyor path for transporting articles through an x-ray beam.
2. Description of the Prior Art
Baggage inspection systems are common, wherein a moving conveyor transports articles between an x-ray source and a radiation detector for inspecting the articles by means of an x-ray beam generated by the source. The articles are moved by the conveyor at a defined speed and are scanned in strips. Samples are acquired by integrating the signals from individual detectors comprising the radiation detector, with the number of such samples depending upon the number of individual detectors within a given row. The samples are converted into digital form and are written into a memory, and are then used to compile a video image of the article. Inspection of the article is then undertaken on a monitor which may, for example, comprise 576 lines in accordance with the European video standard. The signal for an individual detector is represented on the monitor by one line, so that the number of individual detectors is accordingly limited to 576.
The row-shaped radiation detectors are not subject to limitation as to length and shape, so that this technology is utilized in an increasing degree by employing very long rows for transilluminating articles, such as baggage articles, having extremely large dimensions.
Such rows are generally formed by a plurality of structurally identical modules, which contain a selected plurality of individual detectors arranged in one row at uniform intervals in accordance with their dimensions. A grid dimension is thus selected such that the number of individual detectors required for constructing a row having a defined length optimally corresponds to the number of active, evaluatable individual detectors. Rows having a large grid dimension are therefore utilized in systems for inspecting large baggage articles.
An image scale is thus achieved, wherein the monitor is completely fully written in the vertical direction given an expected maximum size of the articles to be inspected.
If these systems are also employed for transilluminating smaller articles, the x-ray image of the smaller article fills only a very small portion of the picture screen.